Carburetor for internalcombustion engines



July 7, 1953 c. wf GlLMoRE `CARBURETOR FOR INTERNAL-COMBUSTION ENGINES vFiled may s1, 1951 INVENTQR y @fiaba Wzflpza/ ATTORNEYS Patented July 7, 1953 'i Ur-Ig'rlsl) i sT-A1.1E;s PATENT' UFFICE CARBURETOR FOR INTERNAL- COMBUSTIONENQINES H Y n 'Carleton W. Gilmore, Pampa, Tex.';"'Mary-Myrtle Gilmore, independent executrix-ofsaid CarletonfW. Gilmore, deceased f ,Applicationiviayfsr 1951', .seria1Ndazaoos' '8Claims.

'ternal combustion 'engines fand 'particularly 'to "carbureto'rs `Vfor 'engines fusing liquid' -fuels "having "high vapor pressurej'suchas butaneand vpropane, which'Y fuels mustv be kept under'pressures v`ranging from 3U-pounds toI 200 pounds pern square inch', depending'on the compositionof the fuel and the temperatureY to which the'fuel'is subject tin' storage.

- *Anr object `ofi-,his invention is to provide a simvple;"practical, and comparatively inexpensively- ``constructedcarburetor to handle liquid'fuels of l'high vaporpressure -Without vaporizing the fuel prior to its delivery to the carburetor. 'Another -object of this invention is to pro- Vvide `a -carburetor suitable rfor handling liquid `fuels of highpressur'ewherein the fuel-to-air ra- `tio may 'be ma'intainedsubstantially` constant for various engine speeds and loadings, andY wherein saidfratio can be -readilyadjusted -for fuels of 'diierent viscosities. f

The invention consists in the-construction and novel arrangement ofparts, hereinafter fullyfdefscribe'd, illustrated in the accompanying draw- -ings,fand -pointed out Vin ythe claims Vappended khereto. -After considering the embodiment of the invention herein shown and described, lpersons skilled in the art will understand that vari- 'fouslchanges inv the "form, proportion and yminor details of construction'maylbe'madefwithin the fsa-ope of `the appendedclaims, without'departing romthe spirit l and principle of lthe invention.

`Fig.-1-1'is-a vertical, sectional 'view of the car- Vburetor of my invention;

2 is a'sect'ional view takenon the lined-2 o'fFig 1; l v fFig. 3 is a vertical,-sectiona1 View-of the ylower half of Y the carburetor at 190"l to the plane' of-the fsectionrofjzliig 1; v Y l "-Fig. 4 is a diagrammatic vview of the carbu- Aretoriand the mannerin which it is connected to .an engine in use.

Referring to vthe drawings, the embodiment `of :the -invention therein shown comprises a carbu- .retorhaving a'shell or-body portion including an upper part Iv and-,a .lower part 2. These .parts may have any, desired external contourandare .formed; interiorly-i to; provide the main fluid/snow gpassage M throughthei'carburetorwhen the parts I zand' v2 areassembled :as yshown. -lThe parts y--'I and Z'may be.l interconnected.many-desiredy manlner, and are shown fory convenience wvithftheir v :meeting ends intertting and Voverlapped'andf any i.convenient means;- suchv'asr--screws :S5-may bev1 ernfploy'ed- -for-securing these parts together.

jThe partA I' is provided .with conduit means 3 .for delivering'liquidfuel under pressure to `the .carbureton As shown, the conduit 3 extendslat- Verally through an opening .provided ,in theWall k5 ,oi the part I, and is secured'therein by a'nut 5 screw threadedly attachedv to the-protruding end 4 of the conduit. The end 4 of the conduit is adaptedV to be connected'to a source offliquid fuel under pressure. The conduit 3withinlthe lo part I of the carburetor extends upwardly-'and thensubstantially radially ofthe uidiflow'passage `therethrough and lis provided-with'a downwardly directed fueldischarge-orice. A valve tube 'I is Vsecuredto'the conduit 3 in positionto lsf'receiveliquid` -fuel discharged through the-ori- 'fice 6, by anylconvenient-meanssuch 4as 'theco'l- Hlar 8 surrounding and secured to the tube I and in turn attached to the conduit 3 as-shown. The --tube 'l extends downwardly from the conduit 3 20 and the open lower end 9 thereof receives a needle-valve l1I 0, the valve being supported-in an up- Yrig-ht posi-tion and disposed within the down- .wardly directed opening in the-end of the tube 1. The-needle valve Ill is mounted. for'axial move- 25 .ment` within thedischarge end of the tube 'I and Ufor this Apurpose is secured to a plug I I :which-may JbesCrew threadedly Orother-wiseeengaged in the :lower endofaguide tube I 2 .whichiislin turn slid- .ingly mounted @upon '.the'tube 7. "The .plug .II is Yprovided lwith va plurality of fuel dischargeaipas- :sages -Ial a for,J discharging .liquidfuel flowing from the tube .l .when the Lneedle Valve is openinto .the Amixing chamber, .to be later described. Thegtube -.-.I2 has secured jthereto intermediate its ends .a tflowr constrictinggbodyjmember I3. The member kISU 35 -zi3cmaysbe secured rto the tube .I2 inany desired --manner such as'by means of a collar I4 secured by soldering or welding Vto `both .the memberi|3 ,andthe tube. l2. `The flow constricting member 1 I 3 is. positioned .to extend transversely of .the iiuid iflowz-.passagelMand is .preferably yin the formfof gaihollow, generally inverted conical bodymember yprovided with ga' downwardly directed i opening a I5 :theapex thereof. The needle valve .assembly .'iincluding vthe needle valve..zI0,-:the plug II, the tube I2, -and'the flow constrictingmember I3 are `Amovably. mounted; in operative relation .with respect to the: tube lby: means pf axcoilspring'IB supportedfwithin the L lower :part t2 .of the acarbu- 1retor-bymeans of a transverse bar "Il mounted V therein for longitudinal*adjustment'by meansof screw members I8 threadedly engaged with-oppo- Vsite ends of the bar Il and having their .heads I9 positioned externally ofthe part 2 and sup- ,ported on shoulders ISai-or ready access when adjustment `of the bar-1l is required. VAs shown more particularly in Fig. 3, the bar I1, at a point midway of its ends, is provided with an upstanding collar 20 and an axially disposed opening 2I. The lower end of the spring I6 is supported on the barV I1 and surrounds the collar 20 while the upper end of the spring I6 is engaged with the inside surface 22 lof the bottom portion of the hollow member I3 to thus urge the needlevalve assembly upwardly to maintain the needle valve in its closed position under normal conditions.

A mixing tube 23 is positioned centrally of the fluid flow passage M through the carburetor, said tube surrounding the spring I6 and having its upper end somewhat above the lower end of the guide tube I2 and fuel discharge ports Ihr.l The tube 23 is provided at its lower end with diametrically opposed slots 24 to straddle the bar I1 and to permit relative movement between the bar and tube during adjustment of the bar I1 as previously described. The tube 23 is provided with a lateral branch 25 which, as shown, extends through an opening in the side wall of the part 2 of the carburetor and is secured within said wall in any desired manner, such as by soldering. The branch 25 terminates outside of the carburetor and is adapted for connection to a source of heated air such as an air jacket J on the exhaust manifold of an engine to which the carburetor is connected.

It is apparent, in View of the foregoing description, that the spring I6 normally tends to maintain the needle valve Ill in a fully closed position. In order to maintain the needle valve open when an engine to which the carburetor may be connected is idling, a lever 26 is provided, said lever being pivoted intermediate its ends to a depending arm 21 secured to or forming a continuation of the conduit 3 as shown more clearly in Fig. 1.r The lever 2B is positioned so that the inner end 28 thereof is engaged with the collar I4 in the normally closed position of the needle valve.

vThe opposite end of the lever terminates within a cavity 29 formed in the side wall of the part I, and is there connected to a rod 30 extending 'through the side wall of the part I. The rod30 is connected to a diaphragm 3I positioned within a diaphragm chamber 32, said diaphragm chamber being secured to the side wall of the carburetor part I by any suitable means, such as /screws 33. The diaphragm 3| divides the diaphragm chamber in'two parts, and the part of the diaphragm chamber remote from the carburetor body is connected by means of a nipple 34, by

Ymeans not shown, to the intake manifold of the engine, so that when suction is developed inthe intake manifold, the diaphragm 3I movesroutwardly to pull the rod 30 and thus rock the lever V26.inV a direction to depress the inner vend 2'8 i thereof, to cause the needle valve I to open and ,admit fuel to the carburetor when the engine is idling. A spring 35 is mounted within the diaphragm chamber 3l and is arranged to exert pressure on the diaphragm 3I ina direction to maintain the lever 26 in position to permit valve IIJ to close under normal conditions, as shown in Fig. I. Y on the diaphragm 3l may be adjusted by a screw The force exerted by the spring 35 threaded member 36 bearing upon one endof vthe spring so that the extent of opening of the valve I0 during idling may be regulated. If desired, manual means may be provided for opening the needle valve for starting, and such means is shown as a pull rod 30a passing through the side wall ofthe carburetor part I and connected to the lever 26. Preferably, the necessary amount 4 of loose play is provided between the pull rod 30a and the lever 26 so that the operation of the lever 26 by the pull rod 30a will notrinterfere with the suction controlled operation of the lever by the rod 30.

The inside wall of part I of the carburetor body defining thepassage M isr shaped generally like the frustum of an upright conefis generally circular in cross section, so that the cross sectional area of the passage increases in the direction of fluid flow through the carburetor. The member I3 is generally streamlined and is dimensoned with respect to the surrounding conical wall of part I of the carburetor to provide an annular air flow passage 31 which, as the valve is openedv and the member I3 moves downwardly,

increases in cross sectional area to admit correspondingly greater quantities of air. The preferred amount of movement of the needle valve from closed to fully opened position is at least 1/2 inch and not over 2 inches for each 100 horsepower of the engine to which the carburetor is attached. The preferred increase in diameter of the inside wall of part I of the carburetor within the stated operating range of the needlevalve and the body I3 is about ,-36 inch per inch of axial length, but may be varied considerably from this figure. Itis apparent that the greater the diameter change per inch in axial length, the shorter the needle valve movement will be and the less accurately will the fuel-to-air ratio Vof the mixture be controlled. It has been found that by properly proportioning the slope of the inside wall of part I of the carburetor, the taper of the needle valve, the size of the needle valve opening, and vthe strength andv length `of the spring I6, a practically constant fuel-to-air-ratio can be obtained for all engine operating conditions when the kind of fuel and its pressurerare maintained substantially constant. As the fuel pressure is increased or as fuel oflower viscosity is used, more fuel will flow through the same opening of the needle valve and the resulting mixture becomespricher as the needle valve` is opened as the result of more air being -sucked through the carburetor as the engine Vload isrinjcreased. Therefore, the fuel should be supplied to the carburetor by a constant pressure pump P and the needle valve designed for the pressure chosen; 'the lower Vthe pressure, the larger will the needle valve'and valve opening need to be. When using liquid propane as fuel, itis preferred Vthat ,the fuel pump'have a constant-discharge pressure of about 200 poundsgpersquarev inch regardless of the fuel tank pressure. -At this high pressure, the diameter of the needle valve and l the valve opening need be relatively small. How- 'fuel of greater viscosity and resultant smaller .flow through the same needle'valve opening can readily be made by decreasing the compression of spring I6 through the medium of the adjustment screws I8, as previously described.

As previously stated, the branch 25 of thev mix- Ving tube 23 is adapted for connection to asource of hot air such as a jacket ,associated with `the exhaust manifold of the engine to which the Ycarburetor is connected., It is desirable to haveall of the air flowing into the engine vto be filtered by the usual air viilterwhichl maybe attachedto the upper sed. 0f the# Part .l 'pf Phearburemrm a.: conventional manner, 4and to provi`dethe upper partzof thecarburetor'with Aan;op'ening 38'1in `.the wall thereof .zwhich..may,y by means not shown, be placed in communication '.with thev hotv air jacket 'fpreviouslyl referred to. By thisl-means, the diiferencefin' pressurewithin the carburetor ,between'the'holef 38 and the branch 2.5of 'Ithe tube 23 will 'cause afflow of airthrough ithe-hot 'air jacket from the point v38 tofthe-branchl. Thus, `hot airvis discharged .fromthe-Abranch25 4intothe'.mixing-.tube 23.A Y TheY hot .-air thus` delivered t0 the mixing tube-231'divides,part of it going upwardly around the lower en'd ofi-guide tube I2 to mingle :with the liquid fuel issuing from the fuel ducts Ila and thereby warm and vaporizethe -sameto thus `inhibit the' yformation of ice at this `gpoint. `The,mixture .of-'hot air and fuel passes upwardly into the hollow member I3 and thence downwardly and out of the opening lthereof'tol mix withV thel unhea'ted airiowing downwardly"'throu'gh the main ypassage Mof the carburetor.' The other portion of heated/air passes .downwardlylthrough fthe.' tube 23 `4andfc'iut ofthe open' bottom 'thereof tonii'x` witlrthe'fuel mixture flowing downwardly through the carburetor from the part I into the part 2 thereof.

From the foregoing description, it is apparent that the pressure differential existing on the upstream and downstream faces of the member I3 causes axial movement of this member within the carburetor to increase the opening of the needle valve when the load on the engine increases and that by proper design of the slope of the inner wall of the part I of the carburetor which surrounds the member I3, the annular air space 31 may be controlled in all positions of the valve to maintain substantially constant air-tofuel ratio of the mixture for all engine loads when a given fuel is fed to the carburetor under -a given pressure. It is also evident that the delivery of Warm or heated air to the region in which the liquid fuel is discharged from the needle valve precludes the possibilty of icing and at the same time insures a rapid and substantially uniform mixture of the air and discharged fuel. Furthermore, the adjustable mounting of the bar I'I provides a ready means for adjusting and controlling the pressure differential necessary to move the member I3 to open the needle valve in accordance with fuel viscosity.

If desired, suitable guide grooves Ila may be provided in the inner wall of the part 2 of the carburetor to receive the ends of the bar I1 and stabilize the bar during adjustment thereof.

Having thus described my invention, what I claim is:

1. A carburetor comprising a body portion provided with a main fluid flow passage therethrough, conduit means for delivering liquid fuel under pressure to said passage, said conduit means terminating in a discharge orifice positioned substantially axially of said passage and arranged to deliver liquid fuel thereto in the direction of fluid flow therethrough, a needle valve controlling ilo-w of liquid fuel from said orifice, spring means resiliently urging said needle valve to closed position, valve control means including a fluid flow constricting member surrounding said fuel conduit means and disposed transversely of said fluid flow passage and extending radially into close proximity to but spaced from the inner wall of said fluid flow passage to thereby restrict the flow of incoming fluid to the annular space between the periphery of `said fluid flow constricting member and the force ofsaidspring as'the iluid pressure differential increases, vrmeans: deningka `fuel mixing chamberopen at opposite ends, .one end Vof isaid 'fuelzmixing chamber surrounding said fuel discharge'orificeand terminating beneath said 'fluid ilow 'constricting Jmember 'and lout'rofv the llipa't'hofuid'flow -through said 'annular space, hand conduit rmeansfori deliveringgheated air` tofsaid mixingf'chamber. 1

2.' Thecarburetor Y.described-in claim 1 Whereinthe mai-n' 'fuel '-ilowl passage of Vthe carburetor includesiaportion generally con-ical in formfgenerally lci-rcularin cross section, and increasing fin cross 'sectionalarea iii-the direction 'of fluid ilow, said valve control means including an-i-nve'rted, conically'shaped, hollow body member positioned co-axially within said conical'portionof the'fma'in fluid flow passage to provide an annular fluid ow passage surrounding Isaid hollow body member, and wherein the fuel discharge orifice and` needle valve -are positioned co-axially within said hollow body member.

3. The carburetor described in claim 2 wherein said inverted, hollow, conical body member is streamlined to minimize turbulence in the air stream flowing around said hollow body member. l

4. The carburetor described in claim 1 wherein the valve control means includes an inverted, conically-sh-aped, hollow body member within which the needle valve and the fuel'discharge orifice are axially disposed, said hollow, conical, body member being provided with an opening at the apex thereof, and wherein said fuely mixing chamber surrounds the needle Valve and the fuel discharge orifice and discharges upwardly into said hollow body member.

5. The carburetor disclosed in claim 1 wherein means is provided for opening the needle valve for starting fuel ilow comprising a lever member pivotally mounted within the carburetor and having one end thereof overlying said valve control means and engageable therewith when said lever is rocked on its pivot, and means opera-ble from the exterior of the carburetor for rocking said lever to move the valve control means in a direction to open the needle valve to start flow of fuel into the carburetor.

6. The carburetor described in claim 1 wherein means are provided to maintain the needle valve in an open, idling position comprising a diaphragm chamber adapted for operative connection to the suction manifold of an engine, adiaphragm within said chamber, a lever pivoted within the carburetor and including an end portion overlying said valve control means and engageable therewith to open the valve when the lever is rocked on its pivot, and an operative connection between said diaphragmand said lever for rocking the lever in response to intake manifold suction on said diaphragm,to thereby hold open the needle valve for engine idling.

7. A carburetor comprising a body portion provided with a main uid flow passage therethrough, conduit means for delivering liquid fuel under pressure to said passage, said conduit means terminating in a downwardly-directed, openended, axially-disposed, discharge portion, a tubular member slidably mountedon said discharge y portion, said tubular member carrying an up. Wardly-directed needle vvalve projecting within the open end of said discharge portion of the conduit and controlling flow of fuel therefrom, means for supporting the needle valve comprising -a bar disposed transversely of the main fuel passage of theY carburetor, means for adjustably supporting the bar at any one of a plurality of longitudinally-spaced positions Within they carburetor, a helical spring member Supported lat one end on said bar, a flow constricting member carried by said tubular member and extending therefrom transversely of the main fuel flow pase sage of the carburetor, said flow constricting member having a peripheralportion terminating in close proximity to but spaced from the inner Wallof said fluid flow passage and restricting the owof incoming fluid tothe annular space' between said member and the inner Wall of said pas- Sage, the opposite end of said helical spring member engaging said flow constricting member from below and urging it and the needle valve upwardly to close the needle valve, a mixing chamber, surrounding the open end of the dis-charge portion of the fuel'conduit, `and means for? dise charging air from the mixingrchamberiipwardly around the needle valve and fuel discharge portion of the conduitimeans.Y i

8. The carburetor described in claim 7 wherein said mixing chamber comprises' an axially-dis- ;posed, tubular `member open at its opposite ends and provided with a laterally-directed air intake means intermediate its ends, the opening in the mixing chamber at itsl lower end discharging secondary air into the fuel mixture flowing 'down- Wardly through the main fluid flow passage of the carburetor. i

CARLETON W. GILMORE.

Arnold Jan. 22,1952I 

